Srt Marine Systems Share Discussion Threads

[the prophet] 11/9/2016 18:14

Simon Tucker has sent out by email an excellent explanation of S-AIS and how SAT-trak fits in together with it's relationship to ABSEA.

Here it is:


The actual coverage achievable by a terrestrial network varies according to obstacles (buildings, islands, headlands), location of a receiving antenna and of course its height. In addition certain natural phenomena can significantly affect the range of transmissions – ducting be the biggest which can see a transmission from a Class B detected 300 miles away. Therefore all terrestrial systems have coverage gaps, and satellite provides a useful method of filling those coverage gaps. Its well to note that most boats operate within only a few miles of the coastline and a typical coast station will have a reliable range of between 20 and 40nm.

- S-AIS: this is simply the concept of having an AIS receiver on an orbiting satellite. Radio waves travel in a straight line and so, in theory, given the curvature of the earth, they radiate horizontally from an AIS antenna and eventually reach space where they can be intercepted by a passing satellite with an appropriate receiver. However there are massive issues to overcome for standard AIS transmissions to be detected by satellites. 1) Transmission quality deteriorates as they travel through the atmosphere, so by the time they arrive at a satellite they can be significantly corrupted. 2) A satellite needs to be passing when the transmission is passing. 3) AIS uses a slot map system to manage transmissions and maximise transmit reliability – the number of available transmit slots every minute is 4,500 which is a simple calculation of the message size divided by the available band width which in turn is defined by the ITU AIS standards. Its impossible for there to be more than 4500 transmissions per minute and so if there are 4501, one of the transmissions will ‘collide’; with another and not get through. This problem is significantly accentuated for satellites as their antenna foot print is between 3,000km and 5,000km in diameter and so they are potentially seeing many tens of thousands of boats at the same time. Today all AIS satellite systems see a very small percentage of AIS transmissions due to various combinations of these issues. A Class A will transmit every 2 to 10 seconds – so if every 10 seconds, that’s 6 per minute, or 360 per hour, 8,640 per day from one transceiver. In an independent test that we undertook in Asia the average number of transmissions seen across the 3 leading AIS satellite systems was 50 of the possible 8,640 transmissions – with the most being 74 and the worst being 36. As more satellites are put up and continuous coverage is obtained, it is clear that the percentage reception will improve, however, at best this will increase to perhaps 5% or 10% of available transmissions and these will be randomly detected over time, not lovely once per 15mins intervals for each boat. And of course the more boats there are the worse the issue gets.

- SAT-Trak: over the last 2 years SRT has learnt a lot about this area. We know that customers want to fill terrestrial coverage gaps and like with their radar systems will look for satellite based surveillance data. Therefore there is a clear market for satellite AIS tracking data as a supplementary feed to their terrestrial coast station networks which provide real time, zero latency tracking. What we have learnt is that the way to improve the detection rate of satellites for a controlled fleet of vessels is to implement some special modifications to some of the transmissions. The big difference is satellite detection can come from changes in the transceiver. These include, significant increases in transmit power for certain messages, dynamic fleet co-ordination of transmissions in regards to the channels used and their precise timing. These, and a few other changes, along with the target satellite being aware of those changes, can make a significant difference in detection of transmissions from AIS transceivers (any type). Thanks to our core technology we have the ability to customise the way our transceivers operate. SAT-Trak is the brand name of a suite of functionality in the transceivers which can be adjusted and tuned to enable a specific AIS satellite constellation to reliably track the vessel – rather than the normal random, low percentage rate at which standard AIS transmissions are detected. The exact formulation of any given SAT-Trak will depend on the target satellite system and detection rate wanted by the customer. We have branded this capability as the average customer see’s AIS as a non-satellite technology and thus a simple presentation of SAT-Trak = better S-AIS performance makes the marketing of this easier and of course enables customers to look at specifying this into requirements.

- SRT’s S-AIS strategy: as stated above we recognise the long term value of S-AIS to our customers. The first priority of customers is to implement terrestrial monitoring systems and get transceivers onto boats – they then see the gaps and want S-AIS to fill them. There are several S-AIS systems now and more coming – with several countries building their own as you would expect. SRT has unique technologies, products, systems and expertise to design and deliver large scale vessel tracking and MDA systems which empower countries with their own autonomous systems. With SAT-Trak we can optimise our transceivers to deliver greater detection from any AIS constellation and at the same time, where a customer does not have their own national AIS network, select the commercial system offering SRT the best terms for the supply of data and then tune the implementation of SAT-Trak for that specific customer to their network. The data we buy from that network will be resold to the customer as an SRT satellite data product, which we are calling S-MDA. S-MDA is our data product which we source from third party satellite operators (radar, optical, IR, & AIS) which is customised for the specific customer requirements and then fed into the GeoVS system we have provided – with SRT taking a margin. We see the addition of data as a long term strategy and not something which will realise huge incomes in the short term since initially our focus and that of our customers is designing and implementing hugely complex and challenging terrestrial systems and stocking transceivers on boats.

- eE – as per our RNS, our co-operation with eE continues with ABSEA effectively becoming one configuration of SAT-Trak; and we are very happy with that. It became clear to me that we are in the driving seat and were simply creating ABSEA as a jointly owned brand, with 50% of the benefit going to eE when it was 99% SRT in terms of creating and building the brand and value. We still maintain our share of revenue if a transceiver is sold and the SAT-Trak configuration is ABSEA and the transmissions are received and the data sold by eE. But now we have our freedom back, we can pick and choose in the long term.



I hope that the above helps explain this area.

[lavalmy] 11/9/2016 15:12

fft

You see where you are going wrong is this:

The system was designed as line-of-sight, up to 40 nautical miles at best. 4,500 slots was reckoned to be enough to cope with the numbers, which were only expected to be the large boats covered by SOLAS. Within each area, slots are allocated to Class-A devices. But even in this scenario, from above, the satellite would be picking up all the Class A messages (transmitted every 30 seconds, I think) in its footprint, which would equate to the signals from some 6,000 of the smaller areas. There would be numerous devices all transmitting on the same slot. Hence eE came up with way to decollide these transmissions, and later on, got into bed with SRT to decollide the much weaker signals from Class B devices. SRT's role in this was to tweak the transmissions, and obviously they have succeeded to do so without the need for special payload based kit nor sophisticated ground station kit (that eE have developed).

So as you can see, decollision is only necessary when more than 4,500 transmissions per minute are being received by the satellite (and probably long before that). You don't want to confuse boats with slots nor detection rates. The detection rate refers to the ability to detect a specific signal, no matter how many others are on the same slot. AIS devices vary in the frequency of transmission. But a device transmitting once every five minutes will be detected 99.975% of the time within an hour (at the 50% detection rate we were discussing). Over three hours, the chance of it being undetected is minute. And with the six hour history, unusual movements can be flagged up.

[pldazzle] 11/9/2016 13:43

tri
I *think* I follow, but don't you mean "UNdetected" at steps 1, 2 and 3?

[trident5] 11/9/2016 13:32

1. 1000 boats transmit - 500 detected
2. then those 500 boats transmit - 250 detected
3. 250 boats transmit - 125 detected
4. 125 - 64 (ish)
5. 64 - 32
6. 32 - 16
7. 16 - 8
8. 8 -4
9. 4 - 2
10. 2 - 1
11. 1- 0.5
12. 0.5 - 0.25

voila - 999.75 boats detected.

[fft] 11/9/2016 12:52

LaV.


Even 1 hour without a signal being received could be upto 20 miles (more likely 10 miles) which is not good.

btw, can you run the maths by me as to how you got to 99.975% being detected at least once in a 1 hour period, given there are 12 transmits in that time. My brain is hurting !!

If a device transmission isn't being picked up because of signal overload in that particular area, surely the maths is compromised and that boat would have less chance of being picked up ?

[lavalmy] 11/9/2016 11:31

Wrong heading, fft. An identifier transmits every 5 minutes. So after an hour at 50% success, 99.975 % will be detected at least once. They also transmit a six hour history.

[fft] 11/9/2016 10:47

From the same document, it says that s-ais services only detect a small % of possible transmissions. And the optimised way picks up a lot more. But doesn't say how many. Sounds like potentially less than 50% assuming that small is as bad as it sounds.That doesn't sound great. I thought the whole point of an MDM system was to pick up everything that is going on. It only takes one boat to slip through to cause a Mumbai type incident.Is this why the Indians were going for a 12w system ? Less info getting lost or am I on the wrong heading ?

[pldazzle] 11/9/2016 08:04

One intriguing passage that doesn't seem to have been posted here yet:

"Certified and independent field testing shows that SAT-Trak™ technology can uniquely
increase the number of vessels seen and the number of position reports from each vessel seen via satellite by up to a factor of ten." [Whatever that may mean....]

[hjb1] 11/9/2016 00:13

ha ha! let's see what happens if/when the dire update arrives soon.

[yumyum] 10/9/2016 22:51

Thank you all...yes...interesting. eE point out the risks of satellite launches (seems a rather stupid thing to put in their blog?).

Anyway SRT say :

''SAT-Trak™ is a configurable technology which resides entirely in the AIS transceiver and works to dynamically overcome these issues...''

....in other words it does not much matter about which satellite or its technology.
It is quite a big switch. Not sure how unique it will turn out to be but I guess for a year or two it will be hyper-critical. For sure SRT is number one in AIS tranceivers. They will sell shedloads....but hopefully it helps them climch some big MDM contracts. That is what I am waiting for prior to the takeover.

Over the coming week the share price should move sharply up on this news. It may well not do that of course.

I am waiting for the takeover so not too interested if it goes down to hjb1's 30p (which will never happen) or up to ST's next target of 75p. I wait for something significantly beyond the £1.25 ST target....

I think we do know who is the leader in AIS tranceivers. This announcement is a very good thing for SRT.

[countryman5] 10/9/2016 19:11

Money is cheap, companies and institutions are sat on cash not knowing how to invest and get a return. Post Brexit pound is low making UK companies relatively cheap for foreign buyers. First opportunistic takeover offer for unique SRT is probably just around the corner. Hopefully Chairman, LAV and other major shareholders will say NO.

[crazycoops] 10/9/2016 18:19

That would be my hunch too C5

[countryman5] 10/9/2016 13:49

If you are a country with your own satellite capability (India?), you would like Sat-Trak, if however you are without such a facility then ABSEA is your option.

[the prophet] 10/9/2016 11:47

spot on LaV, no way would SRT go for something that was less attractive.

[lavalmy] 10/9/2016 11:36

Unless foot shooting season has opened, I can't see that SRT would deliberately invent something that undercuts their $3 per boat per month via ABSEA and eE.

So that leaves two possibilities. The first is that SRT will be able to get more than that. The second is that no-one was prepared to pay the sort of prices that eE is hoping to charge. Tucker distinctly said at the AGM that they were going to be charging more than the eE rates to Ecuador.

[the prophet] 10/9/2016 10:23

C5

Isn't that an old quote that previously referred to ABSEA though, ie I don't think the quote is a new one, just that the name of the tech has changed!

-if you google that phrase, it comes up on the 'ABSEA' web-site as well as the SAT-trak web-site, although as LaV has pointed out, the ABSEA web-site link is now SAT-trak

[countryman5] 10/9/2016 10:17

'SAT-Trak technology has enabled me to fit our fishing fleet with Identifier AIS transceivers and track them across our entire EEZ at an affordable cost.'
The above quote must have a foundation, no doubt all will be revealed in due course.

[the prophet] 10/9/2016 10:11

Not a million miles away from EE's 'exactTrax' technology, in terms of the name!

[countryman5] 10/9/2016 10:08

For the doubters we now have a name for the new technology developed at SRT. SAT-Trak.

[the prophet] 10/9/2016 09:49

I think we are witnessing ABSEA being erased from the landscape.
From a customers point of view, it probably is not confusing, all they need to know is that with SRT's kit they can satellite track any form of AIS transponder, be it Class A, B, Identifier etc.
No doubt more info will emerge at the next web-cast or at the interims and I'm sure it will all be good.

[lazyj] 10/9/2016 09:43

An excellent quote.

“SAT-Trak technology has enabled me to fit our fishing fleet with Identifier AIS transceivers and track them across our entire EEZ at an affordable cost.”

But it was ABSEA until yesterday. How can anyone have said that?

Exciting times with much potential - even if a little confusing at the moment.